Both friend and business manager to the Beatles, Epstein had worked tirelessly to secure a recording contract for them back in 1962. His efforts had landed them an audition with George Martin, who subsequently signed them to EMI’s Parlophone Records. Since then, Epstein had overseen their growing empire, leaving the Beatles’ free to focus on their music. Harrison said of his passing, “It was a huge void. We didn’t know anything about, you know, our personal business and finances. He’d taken care of everything… It was chaos after that.”

On September 1, within days of Epstein’s death, the Beatles gathered at McCartney’s house in London’s St. John’s Wood and put their minds back to the task of making music. A plan to study Transcendental Meditation at the Maharishi’s retreat in India was put on hold. Magical Mystery Tour was now a top priority. Perhaps they needed something to take their minds off their grief. Or maybe, as Lennon suggested, Epstein’s death put the fear of god into them that their own days were numbered. “I knew that we were in trouble then,” Lennon recalled. “I didn’t really have any misconceptions about our ability to do anything other than play music. I was scared, you know. I thought, We’ve fucking had it now.”

As the creative force behind the film, McCartney had been busy working on the film’s loose script. “He and John sat down, I think in Paul’s place in St. John’s Wood,” recalled Neil Aspinall, the Beatles’ longtime friend and road manager. “And they just drew a circle and then marked it off like the spokes on a wheel. And it was really, ‘We can have a song here, and we can have this here, we can have this dream sequence there, we can have that there,’ and they sort of mapped it out. But it was pretty rough.”

The Beatles had made little headway on Magical Mystery Tour since May. On August 22 and 23, just days before Epstein’s death, they’d attempted to record “Your Mother Should Know” at Chappell Recording Studios, an independent facility in central London (Abbey Road had been booked and unavailable.) But now it was time to knuckle down. On September 5, the Beatles regrouped in the familiar confines of Abbey Road’s large Studio One to do just that, starting with a new Lennon composition, “I Am the Walrus.”

There was a new face on the session: Ken Scott. Like Geoff Emerick, Scott was one of the many young men who’d climbed up through EMI’s rigorous training program. He had worked as second engineer—a tape machine operator—on previous Beatles sessions, but to date he had never engineered a recording. On this day’s session, he was working as second engineer to Emerick, who had engineered nearly every Beatles session from Revolver forward. Emerick’s ingenuity with recording equipment, his ideas about microphone placement and his talent for interpreting and fulfilling the Beatles’ growing desire for audio effects had quickly made him an invaluable part of the group’s production team.

So Scott was understandably shocked when, less than two weeks later, on September 16, he arrived at Abbey Road and was told to take over as the Beatles’ engineer; Emerick had abruptly left for an extended vacation. “I was completely thrown in at the deep end, put behind a board having never touched it before,” Scott recalls. “That first session I had no idea what the hell I was doing.”

Scott did his best and carried on with the session, a remake of “Your Mother Should Know,” using the same mic setups and recording gear that Emerick had been using. Under the circumstances, it’s not surprising that Scott can’t recall what guitars, basses and amps were used on Magical Mystery Tour, but photos, videos and the film offer suggestions. With respect to guitars, the Beatles most likely used the same gear that they used on Sgt. Pepper’s, though it may not appear that way to the untrained eye. As the psychedelic craze caught on in the summer of 1967, Harrison, Lennon and McCartney each gave their guitars wild paint jobs. Harrison treated his 1961 Sonic Blue Stratocaster, acquired in 1965, to a Day-Glo rainbow finish that he applied himself, and redubbed the guitar “Rocky.” He can be seen playing the guitar in the “All You Need Is Love” broadcast, during which he performed his guitar solo live, and in the “I Am the Walrus” segment of Magical Mystery Tour. Likewise, McCartney embellished his Rickenbacker 4001S bass with a dripping pattern using white, silver and red paint; the bass can be seen in the “All You Need Is Love” broadcast, the “I Am the Walrus” segment and the video for the single “Hello, Goodbye,” recorded around the same time as Magical Mystery Tour. Lennon continued to use his Epiphone Casino, which he had spray-painted either white or grey, as well as his Gibson J-160E acoustic-electric, to which he eventually had a psychedelic finish applied.

As for amps, McCartney used a Vox 730 guitar amp—a valve/solid-state hybrid—with a 2x12 730 cabinet for his bass. Lennon and Harrison can both be seen using Vox Conqueror heads with 730 cabinets in the “Hello, Goodbye” video. Other amps in their possession at this time included a Fender Showman, a Fender Bassman head with a 2x12 cabinet, and a Selmer Thunderbird Twin 50 MkII.

Though Scott originally relied on Emerick’s miking and engineering techniques, he found his comfort zone as the weeks stretched on. Eventually, he began to experiment with sounds, much as Emerick had before him. The Beatles’ sessions proved perfect for this. “As a young engineer learning, working with the Beatles was absolutely incredible, for two reasons,” Scott says. “One, there weren’t time limits. With EMI’s traditional three-hour sessions, you didn’t have time to experiment because you had to get a couple of tracks recorded in three hours. With the Beatles, time was unlimited. Two, there was the freedom to experiment. The Beatles always wanted things to sound different, and that gave you the opportunity to try things. I could use completely the wrong mic in completely the wrong place, and completely screw up the EQ so it sounds atrocious. But I would learn from that. And the Beatles could just as easily hear it and say, ‘Oh, that’s awful—but we’ll use it.’” He laughs. “Because they wanted everything to be different. So just in terms of experimentation, they were the most amazing band to be able to work with.”

There was no greater example of experimentation on Magical Mystery Tour than the mono mixdown session for “I Am the Walrus,” on the night of September 29. The song itself was a marvel of wordplay and orchestration—as Lennon said, “one of those that has enough little bitties going to keep you interested even a hundred years later.” No song in the Beatles’ catalog features as many literary and social references in its lyrics as “I Am the Walrus” does. In writing it, Lennon drew on references to Lewis Carroll’s Alice in Wonderland (the walrus), playground nursery rhymes, the Hare Krishna movement, Edgar Allen Poe and even the Beatles’ own “Lucy in the Sky.” Complementing the bizarre lyrics was an equally vivid and evocative orchestral score for strings, horns, clarinet and 16-piece choir, which was recorded on September 27 in Studio One.

But the crowning touch was applied at the September 29 mixdown. Although the song was essentially finished, Lennon wasn’t ready to sign off on the track. “John felt that the song was missing something,” Scott says. Lennon’s idea was to add to the last half of the recording the sound of a radio dial being turned through its frequency range, catching snippets of live programs as well as the static in between stations. But unlike other overdubs, this one would be added live at the mixing stage, thereby embedding the radio broadcast permanently into the final recording. It was an unusual way to work, but with no free tracks available on the four-track tape, it was the only way to proceed.